An Electronic Article Surveillance (EAS) system is designed to prevent unauthorized removal of an item from a controlled area. A typical EAS system may comprise a monitoring system and one or more security tags. The monitoring system may create a surveillance zone at an access point for the controlled area. A security tag may be fastened to an item, such as an article of clothing. If the tagged item enters the surveillance zone, an alarm may be triggered indicating unauthorized removal of the tagged item from the controlled area.
The area comprising the surveillance zone may be limited due to a number of problems. For example, the security tag may produce a relatively weak signal that becomes difficult to detect as the distance between the security tag and detection system increases. The receiver may also have difficulty in discriminating between the signal from the security tag and other signals in the surveillance zone. Consequently, there may be need for improvements in such techniques in a device or network.